posted on 2020-03-20, 14:52authored byRebecca Momper, Heng Zhang, Shuai Chen, Henry Halim, Ewald Johannes, Stoyan Yordanov, Daniele Braga, Balthasar Blülle, David Doblas, Tobias Kraus, Mischa Bonn, Hai I. Wang, Andreas Riedinger
Semiconductor
nanoplatelets exhibit spectrally pure, directional fluorescence. To
make polarized light emission accessible and the charge transport
effective, nanoplatelets have to be collectively oriented in the solid
state. We discovered that the collective nanoplatelets orientation
in monolayers can be controlled kinetically by exploiting the solvent
evaporation rate in self-assembly at liquid interfaces. Our method
avoids insulating additives such as surfactants, making it ideally
suited for optoelectronics. The monolayer films with controlled nanoplatelets
orientation (edge-up or face-down) exhibit long-range ordering of
transition dipole moments and macroscopically polarized light emission.
Furthermore, we unveil that the substantial in-plane electronic coupling
between nanoplatelets enables charge transport through a single nanoplatelets
monolayer, with an efficiency that strongly depends on the orientation
of the nanoplatelets. The ability to kinetically control the assembly
of nanoplatelets into ordered monolayers with tunable optical and
electronic properties paves the way for new applications in optoelectronic
devices.